The present invention relates generally to optical devices, and more particularly to tunable optical devices useful for telecommunication applications.
Fiber optics communications is advancing beyond simple point-to-point links with static signal properties to one of complex networks of nodes, where signals travel different distances and through different types of fibers and amplifiers depending on the time-varying configuration of the network. In such reconfigurable networks, the properties of the signal are often varied depending on how far and through which fiber a signal has traveled to a particular node.
For example, as an optical signal passes through optical fiber, dispersion of the signal accumulates, degrading the quality of the signal. Dispersion of the signal may be a result of chromatic dispersion or possibly polarization dispersion. The extent of chromatic dispersion depends on the wavelength of the signal, the fiber type, and the transmission distance. Polarization dispersion may result due to fiber imperfections or uneven fiber stresses.
To properly receive the signal, the total dispersion generally should be balanced. This may be accomplished through use of a device which supplies an amount of dispersion opposite to that which has been accumulated during transmission. Such devices, however, may be relatively expensive. In addition, such devices may be inflexible in that they do not account for changes in a network over time, whether due to aging or transient environmental factors such as temperature.
Similarly, as a multi-wavelength optical signal passes through a chain of amplifiers, the gain seen by the different wavelengths varies depending on the number of amplifiers, the optical powers of other channels, and the wavelengths themselves. Generally, the power of the signal should be adjusted periodically such that the signal to noise ratios remain within the correct margins. Further, it is often desirable to monitor various parameters related to optical network signal traffic. Unfortunately, devices which allow for varying measurement of different channels passing through a point of an optical network tend to be either expensive, inflexible, or a combination of both.
The present invention provides optical devices and methods. In aspects of the present invention a tunable optical element is provided. In one embodiment the tunable optical element comprises a moveable path changing optical element adapted to receive light in a first optical beam on a first path and provide the light in a second optical beam on a second path, the second path being dependent on the position of the moveable path changing optical element; and a position dependent optical element receiving the light in the second optical beam, the position dependent optical element changing a spectral characteristic of the light depending on the position of receipt of the light in the second optical beam by the position dependent optical element.
In another aspect of the present invention an optical device is provided. In one embodiment the optical device comprises a spatially varying optical unit, the spatially varying optical unit adapted to receive light provided on a plurality of paths, the spatially varying optical unit varying a spectral characteristic of received light depending on the path of the light; and means for providing light to the spatially varying optical unit on any one of the plurality of paths.
In another aspect of the present invention an optical device is provided. In one embodiment the optical device comprises means for reflecting light on a first path to any one of a plurality of second paths; and means for receiving light on at least two of the second paths and changing a spectral characteristic of the light depending on the path of the light.
In another aspect of the present invention a method of changing a spectral characteristic of light is provided. In one embodiment the a method of changing a spectral characteristic of light comprises receiving light on a first path; transferring the light on the first path to a selected path of any one of a plurality of second paths; and changing a spectral characteristic of the light depending on the selected path.
These and other aspects of the present invention will be more fully comprehended upon review of the following discussion in conjunction with the accompanying figures.